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After the engine has warmed it idles rough

Tiny
MBFOR99
  • MEMBER
  • 2000 FORD F-250
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 230,000 MILES
Cranking after it has warmed up and sat for a bit has a very bad lopy idle. Like a lean condition and trying to compensate for it making it lean I found a few things about a IAT sensor, but I cannot find where it is also. Have just replaced the MAF just a few days ago and bought a cheap. EBay one last Aug and just replaced it with a Duralast day before yesterday.
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Tuesday, April 26th, 2022 AT 4:15 PM

11 Replies

Tiny
MBFOR99
  • MEMBER
  • 46 POSTS
  • 2000 FORD F-250
  • 5.4L
  • 4WD
  • AUTOMATIC
  • 230,000 MILES
Lopy idle at idle unless A/C is on and p1132 code changed 02 sensors and new MAF sensor day before yesterday.
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Tuesday, April 26th, 2022 AT 7:35 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

What it's doing sounds related to the idle air control valve (IAC). The IAC is responsible for the idle speed and adjusts when a load is placed on it. For example, the A/C would require the engine to increase the idle.

What I suggest is to remove the IAC on the throttle body. Inspect it and inside the Throttle Body where it mounts for dirt, corrosion, carbon, or anything that can restrict the air passage. Here is a link that explains how to service one:

https://www.2carpros.com/articles/idle-air-control-valve-service

If the pintle on the IAC is in bad condition, replace it. Also, it is important that the air passage through the Throttle Body is clean as well.

If it needs to be replaced, I attached the directions below.

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.
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Tuesday, April 26th, 2022 AT 8:25 PM
Tiny
MBFOR99
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No other codes are thrown, but a p1132, but I will do that in the morning and see what I can find. Thanks for all of the help.
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Tuesday, April 26th, 2022 AT 8:45 PM
Tiny
MBFOR99
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Hello, I changed the IAC valve looked to be an eBay part, very cheap replaced it with a good part. Now after replacing it still had a very lopy idle until I turned it off and re started it. Does it need to be driven a few times for it to relearn?
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Wednesday, April 27th, 2022 AT 5:20 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

Was the throttle body clean where the IAC is attached? Drive it for a bit to see if the idle goes back to normal.

Also, just to confirm. The sensor code was the upstream bank 1 sensor. There are either 3 or 4 sensors on the vehicle. I just want to make sure the correct one was replaced.

See pic below.

Let me know.

Joe

See pic below. Note: One is for the original dual exhaust system and the other is a single exhaust.
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Wednesday, April 27th, 2022 AT 6:54 PM
Tiny
MBFOR99
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Still a very rough idle and yes, both upstream were replaced doesn't have cats so no downstream sensors also was reading it. Could be a faulty ECT sensor?
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Thursday, April 28th, 2022 AT 3:19 AM
Tiny
MBFOR99
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  • 46 POSTS
Maybe an EGR?
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Thursday, April 28th, 2022 AT 10:35 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

If the downstream sensors are missing, that can be the problem. And yes, a faulty EGR can cause it, but I don't believe they used the ECT for air/fuel mixture determination.

If your scan tool has a live data scan tool, before starting the engine in the morning, see what the ECT is signaling. Also, let me know what the short-term fuel trims are once the engine warms up.

I will watch for your reply.

Joe
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Thursday, April 28th, 2022 AT 6:09 PM
Tiny
MBFOR99
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My scan tool doesn't show that, but today this is what I did after I got off work: I cranked my truck and had the same lope horrible idle, so I disconnected the EGR solenoid for a few seconds and re connected it by me doing this it immediately idled out perfect no lope whatsoever. I drove home no problems had amazing power maybe I had lost a connection between the solenoid and the EGR?
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Thursday, April 28th, 2022 AT 6:53 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Anything is possible. See if it continues this way. Hopefully, it was a poor connection.

Let me know if it changes or if I can help in any way.

Take care,

Joe
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Thursday, April 28th, 2022 AT 7:14 PM
Tiny
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Yes, I definitely will. Thank you for all your help. Matt
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Thursday, April 28th, 2022 AT 7:17 PM

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